Earlier this week, I purchased 2 vintage Dacor LP72s. I posted in the basic scuba discussion forum about using steels in tropical seas, and this is the offshoot of that thread...
I bought the tanks based on some grainy photos from the web. After getting them, both tanks are in relatively good shape (at least externally thus far)
The tank numbers are as follows:
DOT-3AA 2250
74345
DACOR
8(L)75+ PST
DOT-3AA 2250
61794
DACOR
10(L)72+ PST
I take it then that these tanks are from 1975 and 1972 respectively. What I'm not sure of is if DACOR was the manufacturer or was PST?
And shouldn't the + sign be after the service pressure?
On the opposite side of the shoulder, both are stamped 1(S)84. So I guess both tanks were re-hydroed back in Jan of 1984. And have not been re-qualified since...
Now, I think the base layer is an epoxy coat, and before I think of doing anyhting more to these tanks I need your opinions.
Summary:
1. Is DACOR the manufacturer or is PST the manufacturer?
2. Are these hot-dipped galvanized tanks?
3. Is the beige layer an epoxy layer
4. Is it safe to assume that the tank is galvanized underneath this layer?
5. What kind of blue paint did they use that it came off like skin?
6. Which would be a better (at this point, easier would be nice) route: Try to get the cream tank gray again (by removing the cream layer - assuming it's galvanized underneath...) OR just use a nice white coat of paint to get both tanks matching :D (appliance white. some rustoleum)
Thanks.
spectrum
May 1st, 2010, 09:41 PM
The L nested in a C in the initial hydro date represents Cochran Labs which did the initial testing for PST.
timegan
May 1st, 2010, 09:57 PM
Hold on there hoss. First thing is, IF your commited to these tanks....[HYDRO/VIS], maybe a tumble is in order as well. Invest your money and time there. Haven't answered your question/s I know, but the answers could be irrelevant without the "PASS". One step at a time.
Doc Ed
May 1st, 2010, 10:21 PM
Yeah, but if they pass, and I paint them, some shop might say that they were tampered with... catch 22.
timegan
May 1st, 2010, 10:55 PM
If they pass? Your good. There are really good Zink coatings, plastic, polymer paints, available. AIR dry only. Just tell em (LDS) non heat cured re-paint. Got a couple of 72s myself. They passed...had to tumble em GOOD. Then 4 coates of Varathane liquide plastic, 220 grit sand between coats. Any dive shop Iv'e taken them, am complemeted on the refinnish. All #s clearly visable, hydro, and vis up to date. Nice tanks! From the pics...it looks like the blue tank was pretty well coated. But too late now.
knowone
May 2nd, 2010, 12:31 AM
Are you tempted to look inside. Hydrochloric will even up ext gal tone.
Doc Ed
May 2nd, 2010, 01:28 AM
Are you tempted to look inside. Hydrochloric will even up ext gal tone.
Tempted - definitely! Valve's still kinda stuck. Gonna knock it off with a spanner and rubber mallet or a cheater bar. Gonna do it :D
As for the acid... I think I'll keep the gal tone as is. Then cover it up with flat white. Off to paint em now! Will post in a bit :D
knowone
May 2nd, 2010, 02:09 AM
Mr valve and mrs chrome probably don't care anymore since you hogwired them to a piece of f king reo.
Doc Ed
May 2nd, 2010, 03:26 AM
Mr valve and mrs chrome probably don't care anymore since you hogwired them to a piece of f king reo.
Yeah, you should see the toolmarks! Good thing I'm sticking these tanks into a manifold.
There was some light rust coming out of the tank. Some fleurettes, but generally the insides were smooth. The dip tubes were covered in some verdigris however.
Time for a tumble.
spectrum
May 2nd, 2010, 07:30 AM
As for the acid... I think I'll keep the gal tone as is. Then cover it up with flat white. Off to paint em now! Will post in a bit :D
The galvanized patina is a beautiful thing. Nothing you can apply will be more durable or timeless.
Gilldiver
May 2nd, 2010, 08:12 AM
1. Is DACOR the manufacturer or is PST the manufacturer?
They were made by Pressed Steel Corp (PST) it is not uncommon to see the exact same tanks with USD on the also.
2. Are these hot-dipped galvanized tanks?
One most defiantly is. The other with the resistant coating most likely is also as there does not seem to be any rust showing through. The un-galvanized tanks I have seen all have at least some spot rust and blistered paint.
3. Is the beige layer an epoxy layer
Most likely, now that it is open to the light you may see some chalking of the primer from UV exposure. If you want to paint them and if the primer is as adherent as I think it should be, use red scotchbright to abrade the surface, do a light prime coat to active the surface, and topcoat as you think fit.
4. Is it safe to assume that the tank is galvanized underneath this layer?
See #2, if you want to be sure, lightly sand a small area to see if you hit the zinc layer.
5. What kind of blue paint did they use that it came off like skin?
Most likely some type of early polyurethane. The yellow paint on USD tanks is like it but I never had the paint come off as easily as this “skin.”
6. Which would be a better (at this point, easier would be nice) route: Try to get the cream tank gray again (by removing the cream layer - assuming it's galvanized underneath...) OR just use a nice white coat of paint to get both tanks matching :D (appliance white. some rustoleum)
In my opinion, anything you get out of Home Desperate will suck for tanks. When I painted my tanks, I used chromated aircraft primer (MIL-PRF-85582) and aircraft top coat (MIL-PRF-85285) gloss white. This system should last many years, if not longer then I will (it is the US Navy’s coating system for aircraft). Outside of the aircraft industry you can’t get these. If you want a good paint job, then go to an automotive supply house and get a high quality primer and paint system from them. Dupont Imron is a nice system, just let them know that it will be applied to galvanize. You can call Dupont and ask what to use. Last, make sure you don’t get a clear coat system as then you will have to add a third clear gloss layer.
Doc Ed
May 2nd, 2010, 09:57 AM
Thank you Gilldiver! :D Best. Post. Ever.
Doc Ed
May 2nd, 2010, 10:05 AM
The galvanized patina is a beautiful thing. Nothing you can apply will be more durable or timeless.
I'd agree, but since I want the tanks to match, and the last time I stripped epoxy off a tank, it took forEVER... I think the easier way out is to simply paint over it.
Haven't sent them in for hydro yet, but I feel soo confident in these tanks that I went out and bought a new regulator (to match the other reg I intend to use on the dubs), and a new isolator manifold...
Thinking of getting a new wing as well...
:D
Doc Ed
May 16th, 2010, 01:25 AM
The tanks passed viz and hydro! :D not bad for 35 and 38 year old tanks :D
Now to go and dive them. I've got a parallel thread to this one regarding my wing selection in the basic forum.
captain
June 9th, 2010, 09:37 AM
Hydrochloric will even up ext gal tone.
Really bad idea, just shortens the life of the galvanize.
mike_s
June 9th, 2010, 10:46 AM
what did you use to strip them?
is it just me, or are they slightly different heights in that doubles picture?
Doc Ed
June 10th, 2010, 05:19 AM
what did you use to strip them?
is it just me, or are they slightly different heights in that doubles picture?
Surprisingly, the paint stripper removed some of the epoxy, and the rest was removed using grease. Elbow grease that is. And lots of fine sand paper. And time.
The photo was taken at a slight angle, so there's some perspective to the photo.
(But yes, there really is an ever so slightly small difference between the two. Weird.)
halocline
June 10th, 2010, 08:09 AM
What bands are those, out of curiosity? Nice job on the tanks. If you ever want to touch up the galvanizing, there's a great product called ZRC galvilite. I stripped my 72s, which were galvanized under paint, then coated them with galvilite. It worked great.
captain
June 10th, 2010, 09:28 AM
If you ever want to touch up the galvanizing, there's a great product called ZRC galvilite. I stripped my 72s, which were galvanized under paint, then coated them with galvilite. It worked great.
Best there is.
Doc Ed
June 11th, 2010, 08:18 AM
What bands are those, out of curiosity? Nice job on the tanks. If you ever want to touch up the galvanizing, there's a great product called ZRC galvilite. I stripped my 72s, which were galvanized under paint, then coated them with galvilite. It worked great.
The bands are custom built. Most of the bands available here were made for AL80s. I have a parallel thread (http://www.scubaboard.com/forums/5278050-post17.html) that discussed it.
I used stripsoll to strip the tanks.
Looked all over the place for a pot of ZRC, but unfortunately, it isn't available here in the Philippines. We do have a lot of yellow chromated zinc primer though - as well as a dearth of environmental controls apparently.
Tropicalwolf
September 1st, 2010, 07:10 AM
Do you have to repaint them for some reason? I kind of like the classic look of just bare metal (one of my tanks is bare).
mike_s
September 1st, 2010, 10:06 AM
Do you have to repaint them for some reason? I kind of like the classic look of just bare metal (one of my tanks is bare).
most folks doing visual inspections on tanks frown upon tanks that have been repainted (other than the factory) because it can hide rust or other imperfections in the tank that might be noted during the visual inspection.
(simply put, if you paint your tank, expect someone at a LDS to give you crap about it.)
